Using all the same site...
https://www.carfolio.com/
...for the figures now I've found one:
1395kg 2017 Cupra 300 Manual 5 Door
1497kg 2017 Golf R 310 Manual 5 Door
1421kg 2017 Cupra 300 DSG 5 Door
1530kg 2017 Golf R 310 DSG 5 Door
1545kg 2017 Cupra 300 ST 4Drive DSG
1593kg 2017 Golf R 310 DSG Estate
So using the estates for reference, the R's 4WD accounts for ~50kg and the extra refinement another ~50kg.
https://www.carfolio.com/
...for the figures now I've found one:
1395kg 2017 Cupra 300 Manual 5 Door
1497kg 2017 Golf R 310 Manual 5 Door
1421kg 2017 Cupra 300 DSG 5 Door
1530kg 2017 Golf R 310 DSG 5 Door
1545kg 2017 Cupra 300 ST 4Drive DSG
1593kg 2017 Golf R 310 DSG Estate
So using the estates for reference, the R's 4WD accounts for ~50kg and the extra refinement another ~50kg.